3,058 research outputs found
Persistence of viable but non-culturable bacteria during the production and distribution of drinking water
The direct measurement of in situ respiring bacteria using 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) shows that, especially for Gram-negative bacteria, large numbers of viable but non-culturable (VBNC) bacteria are present in finished water from a conventional water treatment plant, and the regrowth of bacteria along distribution networks can be seen rapidly by using this very sensitive technique. The level of bacterial inactivation with chlorine is much less important than has been previously supposed (based on experiments with non-injured laboratory strains of bacteria and classical culture techniques). Threshold values of VBNC bacteria leaving water treatment plants or regrowing along distribution systems have to be determined for better control of coliform regrowth and health- risks associated with the consumption of drinking water
Navigating Challenges and Teaching Through Lived Experiences as Graduate Student Instructors
Historically, graduate students across academic disciplines have been expected to teach courses in their field, at the college level, without sufficient guidance. This is known as a stressful and difficult experience, but for some graduate students this can be compounded by their positionality, both in the hierarchy in academia as well as their individual minoritized statuses (racial, sexual, gender, or otherwise.) Brought about by our own experiences and struggles, this paper addresses two primary questions: (1) How do our identities impact our experiences as graduate student instructors? And (2) How do we use lived experiences as sociologists and instructors to create a better learning experience for our students? We answer these questions and end the discussion with a call to action, highlighting anti-racism and disrupting the status quo of academia. The call to action is especially pertinent considering the current social and political tensions laid bare by the COVID-19 pandemic and the continuous fight for racial justice and equity
Cosmological simulations using a static scalar-tensor theory
We present CDM -body cosmological simulations in the framework of
a static general scalar-tensor theory of gravity. Due to the influence of the
non-minimally coupled scalar field, the gravitational potential is modified by
a Yukawa type term, yielding a new structure formation dynamics. We present
some preliminary results and, in particular, we compute the density and
velocity profiles of the most massive group.Comment: 4 pages, 6 figures, to appear in Journal of Physics: Conference
Series: VII Mexican School on Gravitation and Mathematical Physics. 26
November to 1 December 2006, Playa del Carmen, Quintana Roo, Mexic
Expansion-Free Cavity Evolution: Some exact Analytical Models
We consider spherically symmetric distributions of anisotropic fluids with a
central vacuum cavity, evolving under the condition of vanishing expansion
scalar. Some analytical solutions are found satisfying Darmois junction
conditions on both delimiting boundary surfaces, while some others require the
presence of thin shells on either (or both) boundary surfaces. The solutions
here obtained model the evolution of the vacuum cavity and the surrounding
fluid distribution, emerging after a central explosion. This study complements
a previously published work where modeling of the evolution of such kind of
systems was achieved through a different kinematical condition.Comment: 9 pages, Revtex. Typos corrected. Published in Int. J. Mod. Phys.
Atributos microbiolĂłgicos do solo podem explicar nĂveis de produtividade de soja em áreas sob plantio direto no Paraná.
Antitumour Activity of a pt(III) Derivative of 2-Mercaptopyrimidine
The complex [Pt2Cl2(Spym)4], where Spym = 2-mercaptopyrimidine, was synthesized and
analyzed spectroscopically. The presence in the 195Pt NMR spectrum, of only one signal for the Pt(III) indicates the symmetrical arrangement of the ligands and the identical setting of N, S and Cl atoms, PtS2ClN2, for the two Pt atoms being different to other compounds described in the
literature. The interaction of this complex with DNA was studied by several techniques, including circular dichroism, melting temperature determination, electron microscopy (EM) and atomic force
microscopy (TMAFM). Preliminary results show a high activity against HL-60 and HeLa tumour lines for the Pt-2-mercaptopyrimidine complex in comparison with cisplatin activity. Higher values for IC50 were obtained, while the values of LD50 were lower than those for cisplatin
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